Wednesday, February 24, 2010

Evaluating field-goal kickers

In the third quarter of the Super Bowl, the Colts, up by a point, sent in kicker Matt Stover to attempt a 51-yard field goal on fourth-and-11. He missed.

Was the field goal attempt bad strategy? As you would guess, there was a fair amount of second guessing. Carl Bialik, the Wall Street Journal's "Numbers Guy," pointed out one of the more bizarre criticism -- that Stover shouldn't have been sent out because he was too old.

That's bizarre. Jamie Moyer was 46 last year, four years older than Stover. He got blown out a few times, but, after a bad game, you didn't hear journalists and bloggers argue that he shouldn't have pitched because he was too old. Everyone understands that pitchers sometimes have bad games, and it's silly to harp on a single performance. Moreover, age is irrelevant -- what counts is performance. A bad pitcher or bad kicker is just a bad pitcher or bad kicker, whether he's 25 or 45.

My feeling is that the reaction to Stover's miss, the second-guessing and search for causes, is partly a result of the culture of NFL football. In hockey, a player fans on a goalmouth pass, or misses an empty net, and it's unfortunate, but it's part of the game, and there'll be other opportunities later. In baseball, strikeouts happen all the time, even (perhaps especially) to the best players, and they're considered routine.

But in my (limited) experience of watching football, it's different. A dropped pass or a missed block is taken very, very seriously; there's a presumption that every player is expected to make every play, and that every miss isn't just part of the game, but a failure of the player to do his job. A shortstop bobbles a grounder, and life goes on. A receiver lets a pass bounce of his chest, and the announcers are all over him for his lack of concentration and letting his team down.

If you look at the statistics, I'd bet that missed catches are much more common than errors on ground balls. But in baseball, it's just understood that even the best infielders are going to wind up with a few errors over the course of a season. In the NFL, at least in the heat of the moment, it seems like the only acceptable level of performance is 100%.

And that just seems wrong to me. League-wide, a 51-yard field goal attempt is successful only about 55% of the time. Admittedly, Stover has been worse than that, but still, when you try something that succeeds only about half the time, and then it winds up failing, all that second-guessing isn't really called for. Kicking a 51-yard field goal has about the same success rate as making two consecutive foul throws. Has any player in the history of the NBA missed a foul, and then criticized for missing it because he was too old?

I just don't get it. Is it just an NFL perfectionism thing?

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In any case, another thing that strikes me about the NFL is how kickers are evaluated on such small sample sizes. A 30-yard field goal is successful about 90 percent of the time. A kicker misses a couple of those, and suddenly he's a goat, and his job is in jeopardy. Why is that? The chance of a kicker missing two out of three such kicks is about 1 in 37. That's about the same chance of a .300 hitter going 0-for-10. If Albert Pujols did that, everyone would know, from his record, that he's just having a little slump. But if a field goal kicker misses a couple, where's the perspective? It seems like, fairly often, a high-profile miss and a guy loses his job.

I suppose it's possible to think up a situation where that makes sense. If a kicker can go along for years and years, then suddenly lose his abilities overnight, then it might indeed make sense to worry when he uncharacteristically misses a couple. You could easily think up a mathematical model where the team's best strategy is to fire a any kicker who misses two out of three easy kicks. But that doesn't seem realistic to me, even though it's theoretically possible.

Maybe it's that we're not keeping the right statistics. If one kicker is 90%, and another is 85%, well, maybe the first guy kicked for shorter distances, which is why his success rate is higher. If the second kicker went 2-for-4 from 55 yards, that's actually an excellent performance, but it reduces his overall rate. So the success rate may mean very little, especially considering that kickers have fairly similar success rates and that the sample sizes are small.

Why not start by keeping a record of how the kicker does relative to average? If a player makes a 30-yarder, one that normally gets made 90% of the time, he beat the average by 0.1 kicks. If he misses, he's below average by 0.9. Add up all his kicks over all his seasons, and you'd get a reasonably accurate picture of how good he is, at least if he has a reasonably long career. What's Stover's record in that regard? I don't know.

But even so, there are more basic stats we can look at. I can go to his Pro Football Reference page, and see that Stover had a pretty good season, it looks like. He went 9 for 11. He missed one between 30 and 39 yards, and he missed his only attempt of 50+ yards. From 30 yards or less, he's missed only one kick in his last ten seasons. That seems like a reasonable record ... there's nothing there that suggests that there's something wrong when he misses a single 51-yard try in the Super Bowl.

And what I don't understand is why teams don't have a better idea how good a kicker is. If there are only 35 kicks a season on which to evaluate him ... well, how about evaluating him in practice? Get him to kick a few every week, and keep track of how he does. Sure, practice conditions aren't the same as game conditions, but they're better than nothing, aren't they? If you have one guy who makes 75% of 50-yarders on an empty field on a weekday afternoon, and another guy who only makes 50%, isn't that still useful information when you're trying to decide who you're going to sign for next season?

I don't know anything about actually playing the game of football, so this could be completely wrong. But wouldn't it be a good idea to audition kickers by making them kick and seeing how well they do? You could try them at various distances, with good holds and bad holds, with good blockers and bad blockers. I don't know how long it takes to recover after a kick, but if it takes, say, five minutes, you could still get a guy to kick a season's worth of balls in an afternoon. If you think your guy is losing it, can't you just test him out? Why wait until he misses an important kick, then decide he's washed up on that very little evidence?

And here's another idea: is there any predictive value to where the kick goes, rather than just whether it's good or not? I'd think that a boot right down the middle is better than one that just sneaks inside the goal post. If you had tapes of all the kicks, you could give every guy an accuracy score, and see if that has any correlation to future field-goal percentages.

There's gotta be more information out there than "he went 31 for 35 last year." And if you don't have it, it seems like it would be pretty cheap to get.

7 Comments:

Great ideas, I agree with everything that you said. It really bothers me when people freak out over a missed fg attempt, I just say regression and they say wtf? But, what you said is very true and the problem is there's no other sport to compare it to. There are only 16 games a season and every play could be the difference between a win and a loss, that's 1/16. So when Braylon Edwards drops 3 passes that could've let the Jets win another game or if Snachez hadn't thrown a pick a the start of the 4th quarter against the Patriots, the Jets would've won.

Every fan could pick one, two or three plays from any football game and say because this and that didn't happen or because player X fumbled we lost the game. In baseball, things with such impact don't usually happen and if they do it might only have impact on 1/162 games which is a joke. Football is based on small sample sizes and therefore every minute mistake will be scrutinized. BTW this is why Peyton is the best player ever.

Don't forget that kicking a 42 yard field goal is different in a blustery 15 degree Green Bay than it is indoors. And both a different than kicking that 42 yard field goal in Denver. So the in-game sample size gets knocked down even further because some park effects are there.